Half-width circuit breaker adapter arrangement



Nov. 15, 1966 A. R. NORDEN ETAL 3,286,068

HALF-WIDTH CIRCUIT BREAKER ADAPTER ARRANGEMENT Filed Oct. 21, 1964 ATTORNEY United States Patent York Filed Oct. 21, 1964, Ser. No. 405,488 5 Claims. (Cl. 200166) This invention relates to circuit breakers and panels or load centers therefor, and in particular to an adapter for electrically and mechanically connecting a circuit breaker of a given width to a load center constructed to receive circuit breakers of greater width.

The conventional load center for home and light industrial applications comprises two or more power buses from which bus-blades project in a parallel array; the blades of the buses being alternated so that neighboring blades are associated with opposite polarity buses. The spacing between adjacent blades is approximately one inch and is so designed to accommodate the standard oneinch width circuit breakers.

Several years ago half-inch width circuit breakers made their appearance on the market, and while panelboards may be constructed specifically toutilize what will be hereinafter referred to as half-width breakers} it is highly desirable to utilize existing panelboards adapted for the standard width breakers. In addition, it is often economically desirable to construct a singlepanelboard which will have the flexibility of utilizing both the standard and half width circuit breakers substantially interchangeably.

The conventional circuit breaker, be it single or double pole, is designed with a receptive contact clip centered at the lower front corner. When applied to a bus-blade, the breaker sits astride the blade with the contact clip gripping its opposite sides and one-half of the breaker width overhanging the blade on either side. Since a neighboring unit is likewise disposed on a bus-blade oneinch away, the two units are contiguous. At the point it bears mentioning that further space optimization is achieved by making each bus-blade length sufficient to engage two clip-on units in front-end abutment. Thus it may be said as a general proposition that conventionally the number of clip-on unit pairs equals the number of bus-blades.

The innovation of half-width breakers would at first appear to double the circuit breaker capacity of a given load center. However, it is apparent that the reduced width is not significant in this regard if the conventional clip-on feature is retained since the maximum number of units per blade remains at two.

Accordingly, various arrangements have been developed for optimizing the use of load center space. A standard approach is to produce such half-size breakers as combination pairs. This approach, however, forces the purchase of two units where only one may be required; and also necessitates production and stocking of combination ratings, such as 15-15, 15-20, 2020, 153(), 2030 and 303() amperes.

Another approach calls for a half-width circuit breaker having a :blade contact (i.e. one whose function it is to contact the bus-blade) adapted to appear at either side of the circuit breaker at the front end thereof. Since front end may be defined herein as that portion of the breaker to be operatively positioned in juxtaposed relationship to the load center bus-blade, it may be seen that a pair of half-width breakers may by this arrangement be contiguously disposed between adjacent bus-blades, each contacting its adjacent bus-blade in side-wiping fashion.

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The foregoing, however, is not yet a complete solution since noconsideration has been given to neutralizing the force imparted by the sidewipe, necessary to maintain a good. electrical contact. To vividly illustrate this point, consider a single half width breaker between a pair of standard spaced bus blades; it is apparent that with the force of the contact going unneutralized, the breaker will simply laterally displace itself, destroying the electrical connection'between the breaker and bus-blade.

Accordingly, it is the object of this invention to provide means for adapting narrow circuit breakers, particularly half-inch width breaker-s, to panelboards designed to receive larger width circuit breakers, particularly oneinch breakers. 7

It is a further object of this invention to provide means for properly positioning or seating a half-width circuit breaker unit in a standard panelboard, andrneans for sustaining the contact pressure of the circuit breaker blade contact against its associated bus-bladehis a further object of this invention to satisfy the last mentioned object with a single economical adapter.

It is a still further object of this invention to provide a single adapter for converting an entire colinear array of bus-blades of standardseparation to accommodate halfwidth circuit breakers of' the aforementioned type.

Briefly, the invention is predicated upon the concept of providing a comb-shaped adapter, the slots of which embrace, the standard separation bus-blades, the adapter being furnished with intermediate transversely disposed insulator ribs for positioning the half-width circuit breakers and counteracting the force of the contact.

The above mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will best be understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 illustrates," in partially exploded perspective, the arrangement of circuit breaker, adapter and bus blades according to the invention; and i FIG. 2 is a top sectional View of two pairs of abutting circuit breakersoperationally positioned, with the aid of the adapter, in a bus-blade array.

Referring now to the figures, and in particular toFIG. 1, there may be seen a half-width circuit breaker 10. As is shown, it is conventionally constructed of two mating housing sections 12 and 14, generally of a thermosetting plastic insulator material, joined together by any suitable means such as the rivets 16. The two cooperating sections form a cavity (not shown) within which the blade contact 18 is disposed to emerge from the window 20; the latter being in communication with the cavity. Although not shown in the view of FIG. 1, a similar window is also present on the other side of the circuit breaker for emergence of the contact from that side, when, for example, the adjacent bus-blade lies to the left of the circuit breaker. Sufiice to say that suitable means are provided in the circuit breaker interior for biasing the contact outwardly and positioning it on the appropriate side of the breaker. Although not necessary for an understanding of this invention, a more detailed description of this type breaker may be had by reference to copending application Serial No. 233,738, filed October 29, 1962 now Patent No. 3,198,992 to a common assignee.

Underlying the circuit breaker in the view of FIG. 1 is a linear array of bus-blades, a representative few of which (25, 26 and 27) have been shown. The bus blades are depicted in the conventional load center arrangement with blades 25 and 27 stemming from a bus bar of one polarity and the blade 26 stemming from a bus bar of opposite polarity.

Astride the bus blade is the adapter member 30 which may be likened to a comb because of the slots 31, 32 and 33 for receiving the respective bus blades. The adapter member is composed of high impact insulator material such as molded polycarbonate resin and has formed, preferably integral therewith, a series of laterally disposed insulating ribs 35, 36 and 37, each located intermediate a pair of slots.

The thickness of the insulating ribs is preferably equal to that of the bus-blades, so that the Window frames 22 and 23 of the breaker, recessed for admitting the bus blade, may be applied in a like fashion to the insulating blade.

As may be seen in FIG. 1, the arrangement is especially adaptable to breakers of the type having a recessed face 21, providing clearance for the thickness of the adapter member, and a shoulder 24, which may act as a stopto the downward progress of the circuit breaker front end upon its insertion in the load center. Alternatively, however, the shoulders 38 and 29 provided by the recessed windows may serve this function.

FIG. 2 shows a top sectional view of two pairs of abutting circuit breakers operationally positioned with the aid of the adapter member in a load center bus-blade array. Arrows 40 and 41 illustrate the direction of the side-wiping contact force and the reacting and compensating force of the adapter member, respectively. As mentioned earlier, and as this figure vividly illustrates, in the absence of the adapter member the contact forces would effect a lateral movement of the breakers away from the bus-blade.

In order to prevent skewing of the adapter member, particularly where all of the circuit breaker modules are disposed on one side of the adapter, cooperating slots may also be formed in the bus-blades themselves for interlocking with the adapter slots; the latter having been shortened, of course, so that the height relationship of FIG. 1 may be maintained. It is apparent that this is most easily accomplished when the load center is in the production stage, however,'field modifications may prove desirable under certain circumstances.

For the sake of clarity and to avoid detracting from the invention, only the front end of the circuit breakers have been shown and described. For a description of the rear portions, and their cooperation with the load center, reference may be had to the aforementioned patent to a common assignee.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims. For example, although a circuit breaker having a switchable side-wiping contact has been described in conjunction with the adapter, a breaker having a contact protruding from both sides may also be accommodated. In this case the insulated ribs of the adapter member will also serve the function of isolating adjacent breaker contact blades, and it would therefore prove desirable to enlarge the ribs for this function (the breakers being correspondingly recessed).

We claim:

1. The combination of: a load center having bus-blades of predetermined spacing; a plurality of circuit breakers of a thickness one-half the spacing between adjacent busblades and of the type having a blade contact adapted to appear at either or both sides of the circuit breaker at the front end thereof; an insulator member having a plurality of parallel slots therein, each embracing a busblade; and a plurality of insulator ribs each disposed intermediate a pair of adjacent slots.

2. The combination of: a load center having bus-blades of predetermined spacing; a plurality of circuit breakers of a thickness one-half the spacing between adjacent busblades,. and of the type having a blade contact adapted to appear at either or both sides of the circuit breaker at the'front end thereof; an elongated relatively flat insulator member having a plurality of edge communicating parallel slots therein each embracing a bus-blade; and

, a plurality of transversely mounted insulator ribs each disposed intermediate 2. pair of adjacent slots.

3. The combination claimed in claim 2 in which the insulator ribs are of a height substantially equal to the length of a slot and of a width less than that of a busblade.

4. The combination claimed in claim 2 in which the insulator ribs are of a thickness substantially equal to the thickness of a bus blade.

5. The combination claimed in claim 2 in which the bus-blades are slotted for interlocking with the insulator member slots.

References Cited by the Examiner UNITED STATES PATENTS 7/1962 Amadon 174171 X Notice of Adverse Decision in Interference In Interference No. 95,868 involving Patent No. 3,286,068, A. R. Norden and G. \V. Knecht HALF-WIDTH CIRCUIT BREAKER ADAPTER AR- RANGEMENT, final judgment adverse to the patentees was rendered Mar. 14, 1969, as to claims 1, 2, 3 and 4.

[Ofiicz'al Gazette May 6, 1.969.] 

1. THE COMBINATION OF: A LOAD CENTER HAVING BUS-BLADES OF PREDETERMINED SPACING; A PLURALITY OF CIRCUIT BREAKERS OF A THICKNESS ONE-HALF THE SPACING BETWEEN ADJACENT BUSBLADES AND OF THE TYPE HAVING A BLADE CONTACT ADAPTED TO APPEAR AT EITHER OR BOTH SIDES OF THE CIRCUIT BREAKER AT THE FRONT END THEREOF; AN INSULATOR MEMBER HAVING A PLURALITY OF PARALLEL SLOTS THEREIN, EACH EMBRACING A BUSBLADE; AND A PLURALITY OF INSULATOR RIBS EACH DISPOSED INTERMEDIATE A PAIR OF ADJACENT SLOTS. 